Modern electronic devices utilizing microcontrollers and central processing units (CPUs) on one hand have to provide a desired performance, e.g. a given number of calculations in a given time. On the other hand they should be as power-efficient as possible. In particular, they should not require more power than necessary to perform certain tasks. This is particularly true for mobile electronic devices or devices which operate on batteries. Also, microcontrollers performing on-line control and signal measurement with post-processing, e.g. modern power monitoring devices for households, are required to provide high peak performance and low overall power consumption.
The power consumption of an electronic device is closely connected to the clock frequency with which it is operated. The higher the clock frequency, the higher the power it requires. Thus, to reduce the power consumption of an electronic device, the clock frequency the device is operated with can be lowered. However, the clock frequency also determines the computational performance of the device. In modern electronic device hence there are often used methods dynamically controlling the clock frequency to achieve a compromise between high performance and low power consumption.